Comparative chemical neuroanatomy of mammalian posterior pituitary ⅰ. comparative distributions of substance P immunoreactive nerve fibers in the posterior pituitary of the human being, the monkey, the dog, the cat and the rat 哺乳动物垂体后叶比较化学神经解剖学Ⅰ.P物质免疫反应神经纤维在人、猴、狗、猫及大鼠垂体后叶的分布比较